[Requirements for product quality of theophylline sustained-release preparations]

In consideration of the narrow therapeutic range and the pharmacology of theophylline (CAS 58-55-9), the pharmaceutic quality of sustained release theophylline preparations should be monitored carefully. During the last few years, the following pharmacokinetic study programme was established as quality criterion to verify the safety and predictability of theophylline concentration-time profiles: bioequivalence from batch to batch, lack of relevant food interaction, lack of relevant gastrointestinal pH or surfactant effects on absorption, pharmacokinetic profile following once-a-day and twice-a-day application, and pharmacokinetics in high-clearance patients. Smooth, predictable and safe concentration-time profiles can be guaranteed exclusively for preparations which fulfill all these quality criteria. Only such high quality formulations allow to reduce or even avoid therapeutic drug monitoring and can be considered as safe and effective drugs for the chronic treatment of asthma.